Python iterator for kv-store

lmdb_reader.py

import lmdb
import leveldb

def lmdb_reader(filename, **kwargs):
    with lmdb.open(filename, readonly=True, create=False, **kwargs) as env:
        with env.begin() as txn:
            with txn.cursor() as cursor:
                for key, value in cursor:
                    yield key, value

def lmdb_writer(filename, iterator, **kwargs):
    with lmdb.open(filename, map_size=(1 << 40), create=True) as env:
        with env.begin(write=True, **kwargs) as txn:
            for key, value in iterator:
                txn.put(key, value)

def leveldb_reader(filename, **kwargs):
    """Read key-value pairs from LevelDB."""
    database = leveldb.LevelDB(filename, **kwargs)
    for key, value in database.RangeIter():
        yield key, value